ABSTRACT: This paper examines the application of the 'dishonesty' requirement in the cartel offence in the Enterprise Act 2002. It provides an outline of the main issues with the 'dishonesty' element and the struggle of the courts to apply such an illusive provision in antitrust court proceedings. The paper concludes that the new cartel offence in the Enterprise and Regulatory Reform Act 2013 does not go far to amend the issues. It is proposed that a 'per se' stipulation of the cartel offence will achieve the deterrent effect the government aimed for at the start of its competition law reform in the early 2000s.